Sources close to Donald Trump say the president is contemplating halting the payment of government subsidies under Obamacare.
The move would provoke a crisis in the health care insurance market and would likely be aimed at pressuring Democrats into negotiating an alternative to Obamacare, Politico reported.
Trump allegedly proposed the move at a White House meeting with aides May 16.
Some have tried to persuade him not to take such action, fearing that it could backfire and provoke public anger if people lose their insurance.
Mick Mulvaney, Trump's budget director, is reportedly "agnostic" about the proposal and has suggested alternatives to Trump.
The White House has pledged to continue subsidies until the end of May, but has made no commitments thereafter.
"No final decisions have been made at this time, and all options are on the table," a statement from the Trump administration said, according to Politico.
The subsidies were paid by the Obama administration, but congressional Republicans have launched a lawsuit which argues that they must be approved by Congress.
Health insurers are responding to the mounting uncertainty by preparing a significant hike in Obamacare premiums, according to a Los Angeles Times report.
"It's hard to know who's home," a chief executive of one health insurer told the Times. "We don't know who is making decisions."
The Trump administration and Republican politicians argue that the problems stem from the original Obamacare law. As evidence, they have cited moves by major insurance providers like Humana and United Health to stop selling Obamacare plans.
"Obamacare has failed," said Health and Human Services spokesperson Alleigh Marre. "For this reason, Republicans are reforming health care so it delivers access to quality, affordable coverage to the American people."
In Maryland, the state's main insurer is planning to hike rates by more than 50 percent in 2018.
"There has been uncertainty with the Affordable Care Act since it started," Maryland Insurance Commissioner Al Redmer Jr., a Republican, told the Times.
Other commissioners argue the Trump administration has exacerbated the problem. As well as the lack of clarity on subsidies, they point to the federal government's failure to confirm whether it will enforce penalties against people who do not buy insurance.
Molina Healthcare, which offers Obamacare plans in several states, warned earlier in May in a letter that a move by the Trump administration to cut subsidies, known as cost-sharing reductions, could prove disastrous for Obamacare markets.
"If the federal government's full CSR funding commitments are in jeopardy, we believe that the viability of the exchange market is in immediate jeopardy of failing," a letter from Molina's Peter Adler stated.